JPH025143Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a rod rotation prevention device for a linear actuator in which the rod is moved forward and backward by a motor.

Prior Art The above-mentioned linear actuator has a structure in which a nut fixed to a rod is screwed onto a motor-driven screw shaft, and the rod is moved forward and backward by reversible rotation of the screw shaft.Therefore, the nut needs to be equipped with a rotation prevention device. There is. FIGS. 6 to 8 show various conventional nut rotation prevention devices. The one in FIG. This is an example in which a pair of parallel rods 4 are supported on a tip fitting 6 of an outer cylinder 5 so as to be guided and slidable, and the tips of the rods are connected by a fitting 7. However, in this conventional example, machining of the end fitting 6 of the nut is troublesome, and when the stroke becomes large, the rod tends to become twisted or vibrate. In addition, the one in FIG. 7 is an example in which a pin 9 fixed to a nut 8 engages in a long hole 11 of an inner cylinder 10 surrounding the nut to prevent rotation, but in this example, the inner cylinder 10 is In addition, there is a drawback that machining of the elongated hole 11 is troublesome. 8 is an example in which a key rod 13 is welded and fixed in the axial direction within the outer cylinder 12, and a key groove provided in a nut 14 is fitted into the key rod 13. In this example, welding distortion is likely to occur in the outer cylinder 12, which has a poor appearance, and a long stroke makes processing difficult.

Problems to be Solved by the Invention In view of the above-mentioned drawbacks of the prior art, the present invention aims to provide a linear actuator that is easy to manufacture, operates smoothly even with a large stroke, and has a good appearance.

Means to Solve the Problems The present invention proposes a self-lubricating synthetic resin that is screwed onto an electric screw shaft protruding into the rod at the rear end of a hollow rod that is freely guided and slidably supported at the tip of the outer cylinder. A rod rotation prevention device for a linear actuator, in which a nut is fixed, and a ball that partially fits into a spherical recess provided on the outer circumferential surface of the nut is inserted into an axial groove provided on the inner surface of the outer cylinder. The main structure of this paper is as follows.

Function In the above structure, the ball rolls smoothly in the recess and groove with little resistance to stop the nut from rotating, and the groove can also be formed in a spiral shape to allow the rod to rotate as it advances or retreats. It is easy to use and can easily be adapted to applications requiring such rotation.

Embodiment In FIG. 1, the main body 15 has a front flange 16
and a rear flange 17, and a front flange 16.
A rod receiver 19 is fixed to the tip of an outer cylinder 18 fixed to the rod. A pair of collars 21 having an L-shaped cross section are fitted into the center hole 20 of the main body 15, a compression spring 22 is inserted between them, and the spring 22 is held at a predetermined preloaded state by a retaining ring 23. Bearing 24 attached to collar 21
The base end 2 of the screw shaft 25 has a slightly smaller diameter than this.
6 is supported on the shaft.

The screw shaft 25 has approximately the same length as the outer cylinder 18, and
A cylindrical rod 28 fixed by a spring pin to a nut 27 screwed into the rod 5 is slidably guided and supported by the rod receiver 19, and the tip of the rod 28 is connected to a driven machine (not shown) by a pin 29. Rotation of a DC motor 30 attached to the rear flange 17 is transmitted to the screw shaft base end 26 via a differential gear device 31 attached to the rear flange and a spline.

The nut 27 is made of a self-lubricating synthetic resin, and its outer peripheral surface is connected to the outer cylinder 18 as shown in FIG.
, and a spherical recess 3 on the outer peripheral surface.
2 is formed. On the other hand, a concave groove 33 with an arcuate or chevron-shaped cross section extending in the axial direction is formed on the inner surface of the outer cylinder 18, and the nut 27 is prevented from rotating by a ball 34 that fits into both the concave groove 32 and the concave groove 33. Ru. A plurality of balls 34 (FIG. 4) may be provided. Such a groove 33 can be easily formed by broaching a drawn pipe.

By forming the concave groove 33 in a spiral shape with a pitch much larger than the thread pitch of the screw shaft 25, the rod 28 can be given a rotational motion as well as a linear motion.

Effects of the invention This invention has the above-mentioned configuration, and since the balls are in rolling contact with the outer cylinder and are lubricated with the nut, the motion resistance of the rod is small, and the rod is particularly susceptible to lateral loads. In addition to being advantageous when moving forward and backward while being supported by the rod, there is no twisting or chatter as in the conventional case, and the rod can easily be used in applications where the rod performs a compound movement of linear movement and rotational movement.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of an embodiment of the present invention;
3 is an enlarged longitudinal sectional view and a side view of the main part of the present invention, FIGS. 4 and 5 are enlarged longitudinal sectional views and side views of the main part of a different embodiment of the invention, and FIGS. Figure 7,
FIG. 8 is a schematic longitudinal sectional view of a different conventional example. 18...Outer cylinder, 25...Electric screw shaft, 27...
Nut, 28... Rod, 32... Hollow, 33...
...concave groove, 34...ball.

Claims (1)

[Scope of utility model registration request] A nut made of a self-lubricating synthetic resin is fixed to the rear end of a hollow rod that is freely guided and supported by the tip of the outer cylinder, and is screwed onto an electric screw shaft protruding into the rod. A rod rotation prevention device for a linear actuator, in which a ball that partially fits into a spherical recess provided in the outer cylinder is fitted into an axial groove provided on the inner surface of the outer cylinder.